1. Field
Example embodiments herein relates to an apparatus for receiving a signal, and more particularly, to an apparatus for receiving a signal preventing deterioration of receiving performance due to a mismatch between an in-phase I signal and a quadrature-phase Q signal and a method of compensating a phase mismatch thereof.
2. Related Art
Generally, an apparatus for receiving a signal in a communication system, that is, a receiver includes a low noise amplifier (LNA). The low noise amplifier (LNA) amplifies a signal of a received signal mixed with a noise on a wireless channel while suppressing the noise. The receiver processes an output signal of the low noise amplifier by wireless.
In the case that an output signal of the low noise amplifier (LNA) is processed by wireless, the receiver down-converts a received signal to generate an in-phase (hereinafter it is referred to as I) signal and a quadrature-phase (hereinafter it is referred to as Q). A phase difference of 90° exists between the I signal and the Q signal.
The receiver includes a local oscillator (LO) and a mixer to generate an I signal and a Q signal. The local oscillator (LO) generates a local oscillating signal and the local oscillating signal is outputted to a first mixer generating an I signal and to a second mixer generating a Q signal. Each of the first mixer and the second mixer mixes an output signal of the low noise amplifier and a local oscillating signal to generate an I signal and a Q signal respectively. The I and Q signals outputted from each of the first mixer and the second mixer pass through a band pass filter to be band pass-filtered. After that, the band pass-filtered signals pass through an analog to digital converter (ADC) to be converted into digital signals and received in the receiver.
The I signal and the Q signal outputted from each of the mixers should have a phase difference of 90°. In the case that the I signal and the Q signal do not have a phase difference of 90° due to performance of the mixers, a mismatch occurs between the I signal and the Q signal. A mismatch between the I signal and the Q signal distorts a base band signal received to deteriorate receiving performance of the receiver.